Elastic yarn process and product



United States Patent 3,396,529 ELASTIC YARN PROCESS AND PRODUCT Otto T.Stutz, Wattwil, Switzerland, assignor to Heberlein Patent Corporation,New York, N.Y., a corporation of New York No Drawing. Filed Dec. 29,1965, Ser. No. 517,422 Claims priority, applicatigri/sggitzerland, Jan.13, 1965,

24 Claims. (Cl. 57140) ABSTRACT OF THE DISCLOSURE A process comprisingtemporarily high-twisting a synthetic multifilament yarn having at leastone coarse filament with a titer greater than 6 denier and a pluralityof finer individual filaments having a titer less than 6 denier,heat-setting the highly twisted yarn, and then releasing the twist; andsynthetic multifilament yarns so produced.

This invention relates to an elastic yarn process and product, and moreparticularly, it relates to a process for making a highly elastic yarnand to the novel yarn obtained thereby.

It is known that elastic crimped yarn can be made by temporaryhigh-twisting of synthetic multifilament yarns and heat-setting theyarns while they are temporarily highly twisted. Attempts have also beenmade to manufacture yarns having a high elastic extension by theaforesaid temporary high-twisting and heat-setting. A yarn with a highelastic extension is one which resists any elongation or tensile stressand resumes its original shape and length as quickly and as completelyas possible after relaxation of the stress.

In prior attempts to produce yarns with high elastic extension,multifilament yarns consisting of individual filaments with a titer of3-4 denier have been subjected to temporary high-twisting by means of afalse-twisting device and heat-set in the highly twisted state attemperatures which are relatively close to the fusion point of the fibermaterial. Thereafter, two yarns which have been hightwisted in oppositedirections are ply-twisted with a relatively large twist on the order of200-400 turns per meter. These attempts to make a highly elastic yarnhave produced unsatisfactory products, however, because relativelycoarse filaments have been used in order to obtain the high elasticextension, and a rough, undesirable hand which is unsuitable for textilematerials is obtained.

This inventiion provides a process for the production of a highlyelastic yarn which has a desirable hand. This invention also provides ahighly elastic yarn with a desirable hand suitable for textile uses.

Further and more specific objects, features, and advantages will clearlyappear from the detailed description given below.

The invention comprises the novel products as well as the novelprocesses and steps of processes according to which such products aremanufactured, the specific embodiments of which are hereinafterdescribed by way of example and in accordance with which it is presentlypreferred to practice the invention.

Briefly, the process of this invention comprises temporarilyhigh-twisting a multifilament yarn containing at least one syntheticcore filament with a titer above about 6 denier and a plurality ofsynthetic filaments having a titer less than 6 denier and heat-settingthe highly twisted multifilament yarn to make the multifilament yarnhighly elastic. The high twist is then released from the yarn. Theproduct of this invention is a highly elastic yarn comprising at leastone highly-twisted and heat-set synthetic filament having a titergreater than about 6 denier and a plu- "ice rality of highly-twisted andheat-set synthetic filaments with a titer less than 6 denier. In certainaspects of this invention, the highly elastic yarn is combined withfurther yarn components.

The highly elastic textile yarn of this invention possesses a highelastic extension and an agreeable soft hand. Accordingly, the yarn ofthis invention is excellent for use in the manufacture of elasticknitwear and woven goods, and such yarn is especially useful for theproduction of sportswear such as ski trousers, swimwear, and the like.Such yarns can be used in lieu of elastomer synthetic stretch yarns.

The yarn of this invention preferably has a total titer of between about30 and about 200 denier. The coarser filament or filaments preferablyhave a titer of from about 8 to about 20 denier, while a plurality offiner individual filaments preferably have individual titers in therange of between about 2 and about 5 denier.

In one aspect of this invention the individual filaments of themultifilament yarn can have differently shaped cross-sections. It is forexample possible to utilize multifilament yarns, the components of whichconsist of individual filaments having a trilobal cross-section.Moreover, in certain embodiments of this invention one or more of thecoarser filaments can be hollow.

The synthetic multifilament yarns can 'be made by laying or otherwisecombining the coarser filament or filaments with the plurality of finerindividual filaments. The multifilament yarns treated according to thisinvention can also be produced directly in the spinning operationthrough the use of a spinneret with differently sized and/ or configuredspinning holes.

The synthetic multifilament yarns of this invention can be made from awide variety of materials. The yarns are composed of synthetics whichare desirably those having a relatively sharp softening or meltingpoint. Thus, the synthetic multifilament yarns of this invention cancomprise polyester fibers such as polyethylene-glycol-terephthalate andthe like or polyolefins such as polypropylene and the like. It isespecially preferred to use multifilament yarns consisting ofpolyamides, such as polyhexamethylene adipamide (nylon 66), condensationproducts of eaminocaproic acid (nylon 6) or ll-aminoundecanoic acid(nylon 11), and the like and combinations thereof.

In certain preferred aspects of this invention the crimped syntheticmultifilament yarn is combined with additional yarn components. Thus thecrimped highly elastic multifilament yarn can be wrapped with staplefibers of natural or synthetic material. Such staple fibers used in thepractice of this invention can be natural fibers of animal or vegetableorigin such as wool, cotton, and the like, artificial fibers such asthose prepared from viscose rayon and the like, or synthetic materialssuch as those set forth above, as well as polyacrylonitrile and thelike.

Moreover, it is advantageous in some instances to plytwist two crimpedsynthetic multifilament yarns which have been temporarily high -twistedin opposite directions. These multifilament yarns can be twisted orply-twisted with from about 50 to about 600 turns per meter. It will beunderstood that one or both of such crimped multifilament yarns can bewrapped with staple fibers prior to ply-twisting them.

The crimping of the multifilament yarns is preferably carried out bymeans of a false-twisting device, wherein the yarns are conductedthrough hot air or over a heated surface after they are temporarilyhighly twisted for the purpose of heat-setting them. In such process thesynthetic yarn is given a temporary high-twist on the order of thousandsof turns per meter and then heated to a temperature somewhat below itsfusion point. The yarn is then cooledto' temperature substantially belowthe fusion point So as permanently "to fix the twist in the yarn and thetwist is released to provide a highly elastic yarn. In the ply-twistingoperation, where desired, various types of twisting machines, such asring or up-twisters with or without a hollow Spindle can be used. Itwill be understood herein that such false-twisting is used in practicingsome aspects of this invention.

The elastic extension of the yarn as used herein is determined accordingto the following procedure:

Five strands of eight turns of yarn, each one meter long, are unwoundfrom cross bobbins on which the yarn is maintained in the tensionedcondition. The unwinding is conducted under sufiicient tension (about0.1 g./denier) so that'the yarn is stretched straight. The yarns arethen immersed for 30 seconds in 60 C. water containing a small quantityof a wetting agent.

The wetted strands are suspended from a hook and weighted while in thewet condition to produce a stress of about 0.2 g./denier, so that thesuspended strands are completely smooth. After remaining under thistension for one minute, the lengths of the five strands (X to X aremeasured. The weights are then removed, and

the strands are dried While hanging freely suspended without any weightsat 50-60 C. When the strands are dry they are weighted to provide astress of 0.02 g./ denier, and after one minute their Weighted lengths(Y to Y are measured.

The elastic extension is then calculated according to the followingequation:

Elastic Extension: 100- The yarns of this invention possess a highelastic extension. Generally these yarns have an elastic extension onthe order of about and above and frequently on the order of about andabove.

The following examples are given to illustrate preferred embodiments ofthe invention as it is now preferred to practice it. It will beunderstood that these examples are illustrative, and the invention isnot to be considered as restricted thereto except as indicated in theappended claims.

EXAMPLE I A 65-denier polyhexamethylene-adipamide (nylon 66)multifilament yarn consisting of four individual filaments with a titerof 10.8 denier each and 17 individual filaments with a titer of about3.1 denier each are temporarily high-twisted at 3100 turns per meter bymeans of a falsetwisting machine and heated in the highly-twisted stateat 235 for 0.4 second.

A second identical yarn is crimped in the same manner, but the falsetwist is imparted in the opposite direction. The two yarns which havebeen false-twisted in opposite twist direction are then ply-twistedtogether at the rate of 270 turns per meter in the .9 direction toproduce the finished yarn.

The yarn so obtained according to this invention exhibits an elasticextension of 33.8%.

- For comparison purposes, a 70-denier nylon 66 yarn composed of 17individual filaments having a titer of about 4.16 denier each, istemporarily high-twisted at 3100 turns per meter by means of a falsetwisting device and heated at 235 C. for approximately 0.4 second in thehighly-twisted configuration.

A second yarn having the same composition is crimped by false-twistingas described above, but in the opposite direction. The two yarns arethen ply-twisted together at 270 turns per meter in the s direction.

The ply-twisted yarn composed of two 23-filament yarns obtained outsidethis invention has elastic extension of 21% EXAMPLE II A 70-denier nylon66 multifilament yarn consisting of two individual filaments with atiter of 15 denier each and 13 individual filaments with a titer ofabout 3 denier each is temporarily high-twisted at 3000 turns per meterand heated at 230 C. for approximately 0.5 second by means of hot air.

A second yarn which is identical is treated in the same way, but istemporarily high-twisted in the opposite direction. The two yarns arethen ply-twisted at 270 turns per meter. The ply-yarn so obtained has anelastic extension of 32.6%.

EXAMPLE III A 70-denier e aminocaproic acid condensation product (nylon6) multifilament yarn consisting of two individual filaments with atiter of 10 denier each and 12 individual filaments with a titer ofabout 4.16 denier each is temporarily high-twisted at 3000 turns permeter and heated in the highly-twisted state at 195 C. for approximately0.8 second by means of hot air.

A second identical yarn is treated in the same way, except that it ishighly-twisted in the opposite direction. The two yarns are thenply-twisted together at 500 turns per meter.

The ply-yarn so obtained possesses a very high elastic extension and anagreeable :soft hand.

EXAMPLE IV A 74-denier polyethyleneglycol-terephthalate multifilamentyarn consisting of 3 individual filaments having a titer of 10 deniereach and 20 individual filaments having a titer of about 2.5 denier eachis temporarily hightwisted on a false-twisting device at 3100 turns permeter and heated at 235 C. for approximately one second in thehighly-twisted state.

A second identical yam is treated in the same manner, but it istemporarily high-twisted in the opposite direction. The two yarns soobtained are ply-twisted in opposite directions at 60 turns per meter.

The ply-yam so obtained has a high elastic extension and a soft handle.

EXAMPLE V Two multifilament yarns crimped as in Example I and consistingof 65 denier nlyon 66 are separately wrapped on a ring-spinning machinewith a wool roving having a metric number of 2.2. The stretching rate inthe wrapping operation is about 30. After wrapping, the wrappedmultifilament synthetic yarns are ply-twisted together at turns permeter.

A combination yarn with high elastic extension and good slip proofnessof the staple fibers is obtained.

What is claimed is:

1. A process for the production of elastic yarn which comprises crimpinga synthetic multifilament yarn having at least one coarse syntheticfilament with a titer greater than about 6 denier and a plurality offiner synthetic filaments having a titer less than 6 denier bytemporarily high-twisting the multifilament yarn, heat-setting themultifilament yam while highly twisted to render such yarn highlyelastic and then releasing the high twist from the heat-set yarn.

2. The process of claim 1 wherein the total titer of the multifilamentyarn is from about 30 to about 200 denier.

3. The process of claim 2 wherein there are two or more coarsefilaments.

4. The process of claim 3 wherein each of the coarse filaments has atitler of from about 8 to about 20 denier.

5. The process of claim 1 wherein each of the plurality of finersynthetic filaments has a titer of between about two and about fivedenier.

6. The process of claim 1 wherein the coarse filaments havecross-sectional shapes different from the cross-sectional shapes of theplurality of finer filaments.

7. The process of claim 6 wherein the coarse filaments have a trilobalcross-section.

8. The process of claim 6 wherein at least one coarse filament ishollow.

9. The process of claim 1 wherein the highly elastic yarn issubsequently combined with at least one other yarn.

10. The process of claim 9 wherein the highly elastic yarn is wrappedwith staple fibers.

11. The process of claim 10 where-in the wrapped highly elastic yarn isfurther ply-twisted with a second similarly prepared wrapped highlyelastic yarn.

12. The process of claim 9 wherein the other yarn component is a similarhighly elastic yarn.

13. A highly elastic crimped synthetic multifilament yarn comprising atleast one coarse synthetic individual filament with a titer greater thanabout 6 denier and a plurality of individual synthetic filaments with atiter less than 6 denier, said yarn having good elastic extensron.

14. The yarn of claim 13 with a total titer in the range of from about30 to about 200 denier.

15. The yarn of claim 13 having two or more coarse filaments.

16. The yarn of claim 15 wherein each of the coarse filaments has atiter of from about 8 to about denier.

17. The yal'n of claim 13 wherein each of the plurality of the finersynthetic filaments has a titer between about two and about five denier.

18. The yarn of claim 13 wherein the coarse filaments havecross-sectional shapes ditterent from the cross-sectional shapes of theplurality of the finer filaments.

19. The yarn of claim 18 wherein the coarse filaments have a trilobalshape.

20. The yarn of claim 18 wherein at least one coarse filament is hollow.

21. The yarn of claim 13 combined with at least one other yarn.

22. The yarn of claim 13 wherein the highly elastic yarn is wrapped withstaple fibers.

23. A ply yarn comprising two crimped synthetic multifilament yarncomponents, each component comprising at least one individual syntheticfilament with a titer greater than about 6 denier and a plurality ofindividual synthetic filaments having a titer less than 6 denier, onecomponent having its twist in the opposite direction to the othercomponent.

24. The yarn of claim 23 wherein both components are staplefiber-wrapped.

References Cited UNITED STATES PATENTS 2,203,721 6/1940 Dingley et al.57-157 2,777,310 1/ 1957 Comer. 2,890,567 6/1959 Taylor et al 571402,991,615 7/1961 Stanton 57144 3,115,745 12/1963 Lathem et al. 571403,220,173 11/1965 Pitzl 57140 3,169,363 2/1965 Martin 57l52 3,306,0812/1967 Miles et a1 57l52 X 2,904,953 9/1959 Groombridge et al.

57157 XR 2,936,569 5/1960 Mull 57157 XR 3,011,302 12/1961 Rupprecht57l52 3,162,995 12/ 1964 Comer et al. 57157 3,196,602 7/1965 Jenkins etal. 57-157 3,309,863 3/1967 Hermes 57163 FRANK J. COHEN, PrimaryExaminer.

DONALD WATKINS, Assistant Examiner.

